I'm trying to install this for my brother and i'm having a hard time with the patches.
The website says "Download and install the appropriate patches in the order they appear, using the links below. Select the three patches for the client you installed:- Does that mean I install all three or just the recent one which is 3.3.5?
Thanks in advance.

I don't understand. Usually the WoW client automatically installs all of the patches in their chronological order for you. Go to the WoW application on your computer and click on it. On the bottom of the popup window, there should be a big black bar. It will be in a red "setup," yellow "available," and green "playable," order. Each has a certain amount of material that the application downloads for you. Once it's ready to launch, the big "play" button gets highlighted. Until then, you cannot click on it. Hope this helps. If you it doesn't, then contact Blizzard tech support and they'll be more than happy to help you (They've helped me big time in the past and they're always very friendly).